Augmented Expression of a Type IV Collagen‐binding Protein in a Highly Metastatic Murine Fibrosarcoma Clone

The adhesive properties of highly and weakly metastatic murine sarcoma (Meth A) clones were investigated. A highly metastatic clone, MH‐02, preferentially adhered to type IV collagen‐coated plastic dishes and to bovine pulmonary arterial endothelial cell‐coated plastic dishes as compared to a weakly metastatic clone, ML‐01. Pretreatment of MH‐02 and ML‐01 cells with antisera against MH‐02 cells resulted in almost equivalent adhesiveness to type IV collagen. Preincubation of (125)I‐radiolabeled tumor cells with the antisera against MH‐02 significantly reduced the arrest of MH‐02 cells in the lung, but ML‐01 cells were not affected. The number of pulmonary metastatic nodules of MH‐02 cells was reduced to the same level as that of ML‐01 cells by preincubation of the tumor cells with the antisera in an experimental metastasis experiment. These results indicated that the high metastatic ability of MH‐02 can be attributed to its preferential adhesiveness to type IV collagen. The type IV collagen‐binding proteins of MH‐02 and ML‐01 were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) and autoradiography. Among several proteins which bound to type IV collagen, expression of a protein with a molecular weight of 29 kD was significantly greater in MH‐02 than in ML‐01. These results suggest that the greater adhesion of highly metastatic MH‐02 cells to type IV collagen is due to enhanced expression of the type IV collagen‐binding 29 kD protein.